Over the last few decades, several types of input devices for generating instructions for computers have been developed. These devices include mice, track balls, keyboards and touch pads. Some of these input devices generate instructions by means of movement with respect to a reference surface such as a support. Such input devices include, for instance, mice. Other input devices are adapted to translate the movement of an object with respect to an active surface of the input device into an instruction for a computer. Such devices include touch pads.
Over time, users have developed certain preferences for using specific input devices for generating specific instructions. For instance, a mouse is specifically adapted to control the movement of a cursor on a computer screen. Touch pads are specifically adapted to allow a user to link specific gestures to functions such as leafing through a number of documents. When using input devices, it should be noted that the friction between the input device and the reference surface on which the input device is used directly influences the comfort of using the input device and the accuracy of the instructions produced.
For a mouse, for example, such friction has an influence on the movement of the mouse with respect to the reference surface and the effort required by the user in moving the cursor on the computer screen from one position to another. When using a mouse, friction reduces both the speed of the user's action as well as the precision of the positioning of the cursor. Further, friction may result in the production of noise when the mouse is moved over the reference surface. Reducing friction would improve mouse gliding and precision. Further, this would help in reducing or even eliminating slip stick, which is the effect that is caused by the difference between static and dynamic friction. For this and other reasons, reducing and controlling the friction between a mouse and a reference surface can significantly enhance the user's experience.
It should be noted that when using a mouse on a reference surface, some friction is needed for comfortable use of the mouse by a user. For instance, a user would not be able to perform the much-used action of double clicking if he was unable to click on the same spot twice. As another example, when the mouse is not being used, the mouse should not move away from the position where the user has left it due to lack of friction. This could happen, for instance, if the reference surface is inclined.
The level of friction between the input device and the reference surface or support is also important for other types of devices, such as touch pads. When using a touch pad, the user moves an object or a finger over or relative to an active surface of the touch pad. The friction between the touch pad and the reference surface should be sufficient to avoid that the device itself is displaced when moving the finger or the object over the active surface. If the friction is not sufficient, the user could end up using two hands to provide instructions to a computer. One hand would be needed to keep the touch pad at a fixed position while the other hand is used to generate instructions on the active surface of the touch pad.
Given their specific advantages when producing instructions, there is a need for providing input devices which allow the combined intuitive and ergonomic input capabilities of two types of input devices. An example would be a device combining the functionality of a touch pad in combination with the conventional two-dimensional functions of a mouse.
None of the conventional input devices allow for an intuitive use of the input with, for instance, the possibility of altering the friction between the input device and a reference surface linked to a specific operating mode of the input device.
Thus, what is needed is an input device which facilitates the use of at least two operating modes, thereby allowing intuitive use of the input device.